Preheat your oven to 350°F (175°C) and lightly grease an 8x5 inch loaf pan.

In a medium mixing bowl, whisk together the flour, baking soda, baking powder, and salt until well combined.

In a separate large bowl, mix the ground flaxseed with water and let it sit for about 5 minutes until it thickens.

Add the mashed bananas, sugar, melted coconut oil, and vanilla extract to the flaxseed mixture. Whisk until smooth.

Carefully fold the dry mixture into the wet mixture until just mixed.

Fold in optional add-ins like vegan chocolate chips or nuts.

Pour the batter into the prepared loaf pan and smooth the top with a spatula.

Bake for about 45 minutes, testing for doneness with a toothpick.

Allow the bread to cool in the pan for about 10 minutes before transferring it to a wire rack.